Paper No. 9
Presentation Time: 10:15 AM
CORRELATION OF DETRITAL ZIRCON PROVENANCE TRENDS WITH PALEOCLIMATE PROXIES TO ASSESS POTENTIAL LATE CRETACEOUS GLACIATION OF ANTARCTICA
OLIVER, Benjamin P., Earth and Ocean Sciences, University of South Carolina, 701 N Sumter St, Columbia, SC 29205, BARBEAU Jr., David L., Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC 29208, DAVIS, Justin T., Department of Earth and Ocean Sciences, University of South Carolina, 701 Sumter Street, EWS 617, University of South Carolina, Columbia, SC 29208, HEMMING, Sidney R., Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, ADAMS, Erin P., Department of Earth & Ocean Sciences, University of South Carolina, 701 Sumter Street EWS 617, Columbia, SC 29208 and GEHRELS, George E., Arizona LaserChron Center, Department of Geosciences, University of Arizona, Tucson, AZ 85721, boliver@geol.sc.edu
Conventional wisdom holds that large-scale glaciation on Antarctica first occurred at the Eocene-Oligocene boundary. However, several high-frequency, high-amplitude excursions in the marine oxygen isotope and eustatic sea level records suggest that Antarctica may have periodically hosted large-scale, if ephemeral, continental glaciers during the Late Cretaceous. While high atmospheric CO2 concentrations and elevated surface temperatures relative to modern characterize much of the Early Cretaceous, Late Cretaceous CO2 concentrations often hovered near modeled thresholds for glaciation/deglaciation. Owing to the lack of exposed Cretaceous strata proximal to possibly glaciated regions, direct sedimentary evidence of these hypothesized glaciations has not yet been found.
Detrital zircon provenance trends in the Larsen basin, a nearly continuous Early Cretaceous-Paleogene succession east of the Antarctic Peninsula, may offer a useful new sedimentary proxy for glacial erosive activity on the continent. We present U/Pb analyses of detrital zircons from 15 Larsen basin sandstones acquired using LA-ICPMS techniques. As expected, Mesozoic ages associated with proximal Antarctic Peninsula source rocks dominate zircon populations in pre-Campanian Larsen sandstones. However, a significant Paleozoic population characterizes sediments deposited around and after the Campanian-Maastricthian boundary, suggesting the abrupt addition of sediments sourced from the continental interior. This major provenance shift is coincident with high-amplitude oscillations in the oxygen isotope and eustatic sea level records, possibly indicating a connection to glacial erosion on the continent.
